The present invention relates to a sewing station for pieces of material with processing stations, for instance for the hemming, trimming or the like, and with a first conveyance device for the pieces of material cut in lengths from a stock source, which delivers these pieces of material to a second conveyance device, which can be raised by means of a lifting device for introduction of the pieces of material and can be lowered for picking up the piece of material and for its further conveyance to at least one work station.
In such a sewing station, pieces of material receive and preserve certain tensions during their manufacture and finishing. It has particularly been proven that following the cutting of pieces of the material coming from a stock supply (uncut length of fabric) the pulled away materials, which generally are woven printed jacquard or have special patterns, must be straightened out, since otherwise subsequent processing of the piece of material can lead to defects, blemishes or obstructions. The tension in the piece of material indeed is modified following the cutting step and causes imprecisely definable oblique positioning of the piece of material. The result of this is that the forward moving or front edge of a piece of material, for instance in the case of hemming of the cut edges, no longer runs flush with the hems which are produced. The result is a defective piece of material.
In order to overcome the aforementioned imperfections, devices are already known (U.S. Pat. No. 3,906,878) which are integrated into the assembly for hemming the piece of material. These devices have endless transport arrangements which should provide alignment corresponding to the original alignment by modification of their rotary velocity. This method however has the drawback that stresses or tensions occur in the pieces of material during and at the same time as the formation of the hem, which subsequently can be modulated only with great difficulty. Correction of the positioning of the piece of material in this case is further complicated in that with the hemming procedure the material already must be guided exactly and securely, which condition however essentially prevents any subsequent position correction. Then when on the one hand the pieces of material are guided securely and without slippage, on the other hand the oblique positioning of the pieces of material can no longer be corrected. Now the hemming assembly is constructed so that the pieces of material can be subjected to correction of their oblique positioning even during the hemming procedure, which is possible only with less secure guiding and control of the pieces of material, and then too a uniform hem formation, especially with different qualities of material, can no longer be guaranteed in this case.